Quy đồng rồi chừ:
2/1 - 15/24 =..........
giúp mik với
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a; \(\dfrac{2}{5}\) x \(\dfrac{3}{4}\) + \(\dfrac{6}{15}\) : \(\dfrac{4}{9}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{2}{5}\) x \(\dfrac{9}{4}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{9}{10}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{45}{10}\)
= \(\dfrac{48}{10}\)
= \(\dfrac{24}{5}\)
b; \(\dfrac{25}{12}\) x \(\dfrac{18}{35}\) x \(\dfrac{63}{24}\)
= \(\dfrac{15}{14}\) x \(\dfrac{63}{24}\)
= \(\dfrac{45}{16}\)
c; 4\(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) : 5\(\dfrac{1}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{2}\) : \(\dfrac{11}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{11}\)
= \(\dfrac{99}{22}\) + \(\dfrac{2}{22}\)
= \(\dfrac{101}{22}\)
Ta có :
15/27>15/30=1/2
Suy ra 15/27>1/2
1/2=12/24>11/24
Suy ra 1/2>11/24
Vậy 15/27>1/2>11/24
\(\frac{3}{15}\)= \(\frac{3:3}{15:3}\) = \(\frac{1}{5}\)
\(\frac{33}{44}\)= \(\frac{33:11}{44:11}\)= \(\frac{3}{4}\)
\(\frac{2}{8}\)= \(\frac{2:2}{8:2}\)= \(\frac{1}{4}\)
\(\frac{1}{5}\)= \(\frac{1\times4}{5\times4}\)= \(\frac{4}{20}\)
\(\frac{3}{4}\)=\(\frac{3\times5}{4\times5}\)= \(\frac{15}{20}\)
\(\frac{1}{4}\)= \(\frac{1\times5}{4\times5}\)= \(\frac{5}{20}\)
\(\frac{9}{12}\)=\(\frac{9:3}{12:3}\) = \(\frac{3}{4}\)
\(\frac{24}{36}\)=\(\frac{24:12}{36:12}\)= \(\frac{2}{3}\)
\(\frac{3}{8}\)= \(\frac{3:1}{8:1}\)= \(\frac{3}{8}\)
\(\frac{3}{4}\)=\(\frac{3\times6}{4\times6}\)= \(\frac{18}{24}\)
\(\frac{2}{3}\)=\(\frac{2\times8}{3\times8}\)=\(\frac{16}{24}\)
\(\frac{3}{8}\)= \(\frac{3\times3}{8\times3}\)=\(\frac{9}{24}\)
3/15= 1/5; 33/44=3/4; 2/8= 1/4
1/5= 1x 4/ 5x4= 4/20; 3/4= 3x 5/ 4x 5= 15/20; 1/4= 1x 5/ 4x 5= 5/20
9/12= 3/4; 24/36= 2/3; 3/8 không rút gọn được
3/4= 3x 6/ 4x6= 18/24; 2/3= 2x 8/ 3x 8= 16/24; 3/8= 3x 3/ 8x 3= 9/24
\(\frac{1}{15}\) và \(-7\)
Biết\(-7=\frac{-7}{1}\)nên MSC là : 15
Ta có:
\(\frac{1}{15}=\frac{1.1}{15.1}=\frac{1}{15}\)
\(\frac{-7}{1}=\frac{-7.15}{1.15}=\frac{-105}{15}\)
Vậy quy đồng mẫu số các phân số \(\frac{1}{15}\) và \(-7\) ta được \(\frac{1}{15}\) và \(\frac{-105}{15}\)
Câu 1:
MSC=60
7/10=7.6/10.6=42/60 5/-12=-5/12=-5.5/12.5=-25/60
Câu 2:
17/34=1/2; -12/22=-6/11; -25/35=-5/7; 125/75=5/3
Câu 3:
MSC=24
1/3=1.8/3.8=8/24 -3/8=-3.3/8.3=-9/24 17/24=17/24
48/24-15/24=33/24
2/1 - 15/24 = 48/24 - 15/24 = 11/8